نشریه جغرافیا و مخاطرات محیطی
پیاپی 3 (پاییز 1391)

The aim of present study Designated drought regions of Gilan using rainfall anomaly index And cluster - distance analysis. Results showed that by testing different methods to determine the number of clusters، the best method is the entering method and for determining the distance between the classes of common methods، the Euclidean distance method is most appropriate. Finally، 4 clusters with percent of acceptable similarity in the same drought areas in the province were identified. According to the results of analysis of the drought the second cluster، first، fourth and third priorities are in danger of drought.

Because of the vital role of water in human life، examining the phenomenon of climate change effects on drought severity and frequency is important for any area of interest. Nowadays، climate Researchers considers the effects of climate change and climate simulations by using the atmospheric-ocean general circulation models. To achieve the prediction of climatologically parameters، various statistical and dynamical models have been developed to simulate and downscaling of GCM output models. The statistical model of LARS-WG is such a model، which is very powerful for this aspect.

Introduction Active Mending Rivers are the most dynamic and sensitive parts of the fluvial landscapes. Meandering rivers suffer a large Geomorphic changes during the annual flood events. Based on large flood evidences، reconstruction of the channel bed migration will be possible، which is use for Evaluation of future Evaluation and flood risk assessment in the flood plain areas. The morphological evolution of river meanders has been analysed by many authors and various pattern and models has been suggested (eg. Alfredo 2010، chen 2006، Hook 2008، Borisova 2006). Many researchers have examined the morphological impacts of floods and some studies of channel instability have combined time scales، examined the combined effects of flood phases and demonstrated temporal and spatial variability of stream stability. There are many meandering rivers passing from flood Palin areas in Iran which are studied by Iranian researchers (eg. Bayati Khatibi 2012، Rezaei moghadam and khoshdel 2009، Yamani 2008، Jahadi Toroghi and Hosseinzadeh 2012). The purpose of this paper is to demonstrate of active channel changes of Aji-Chay River over the time and assessment of flood occurrence potential based on disptacement of bending river course.

Soil erosion as one of the main causes of soil degradation، annually loss large volumes fertile soils around the world. CORINE model applies for assessing and estimating soil erosion risk. To calculate actual soil erosion، estimating erodibility، erosivity، slope، landuse and vegetation is needed. In this research the CORINE method was modified based on local condition of Jahrom watershed basin as case study.

The priorities of environmental protection planning. In between there and the location had the greatest role and its importance is when the adverse effects of environmental neglect، can cause irreparable. Locate one of these cases، especially in the surrounding towns and cities have landfills. In this study، multi-criteria decision analysis method based on GIS suitable for landfill site selection has been studied in Mashhad. Multi-criteria decision making framework to include environmental factors and socio - economic factors using fuzzy membership functions are standardized and based on the method Analytical Hierarchy Process (AHP) and the mean weight was measured sequentially (OWA) to integrate and are combined. AHP method is used to extract properties of weights be the OWA operator function in a wide range of options making the decision to show the uncertainty associated with the interaction of several criteria used to work. The advantage of this method is that different OWA scenarios suitable landfill sites in the scale between zero and one that represents. OWA scenarios to quantify risk levels (i. e.، optimistic، pessimistic، and neutral) are intended to facilitate better understanding of the patterns involved in the decision process to decide which of the options appear. The appropriate places in this paper based on the models in three scenarios be identified and used to locate a landfill has been introduced around the city of Mashhad.

greater range of vulnerability to disturbances that human induced than many landscapes. The combination of extreme geomorphic events with exceptional population growth and land use modifications underlies the urgency of better understanding of these interactions for investigating of the effects of drivers of change on landforms and landscapes. The combination of natural and human factors provides conditions for these unstable events within the geomorphic transport processes. The present study focuses on the identification of the Kan watershed topple initiation factors and the susceptibility ratio zonation of this event using fuzzy logical model. The distance to road، distance to lineament، distance to fault، slope، aspect، slope formation، elevation، land cover، cryoclastic، thermoclastic، the characteristics of the bed rock anddrainage densitylayers are introduced to the model and fuzzy functions are performed (applied)

Based on linear function، regions near of drainage and fault has possible occurrence more of landslide. Can be that fault and drainage has most influence on the occurrence of landslide hazard. After these two، will influence geology agent (shear andesitic lavas and lava flows). According to polynomial function the distance from fault and drainage has a significant role in susceptibility basin to landslide. Also geological factors (crystal tuff and ash tuff green tuff and locally cut the limestone strata، cutting andesite lavas and lava flows، and rhyolite tuffs with some shale strata) are effective on landslide. Based on radial function distance from fault and drainage has significant role in susceptibility basin to landslide hazard. Also elevation and geological factors (shear andesitic lavas and lava flows، tuffs and rhyolite strata in areas with shale، siltstone، and shale alternation of tuff، crystal tuff and ash green tuff، tuff cut and local limestone strata) has caused considerable influence the landslides. According to sigmoid function distance from fault and drainage has significant role in susceptibility basin to landslide hazard. Also geology and elevation agents has significant role in basin susceptibility to landslides.